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Monitoring Solar Power Plants

If malfunctions with PV plants are not immediately detected, this leads to high yield losses. However, with a professional monitoring system, this problem can be avoided or minimized. Yet, there are numbers of explicit opportunities and challenges that professional PV monitoring presents.

Only a professional monitoring system detects PV plant malfunctions at once. The system monitors and triggers an alarm directly when a problem occurs. The web portal provides detailed visualization of all important plant data and makes it possible for the installer or PV operator to carry out a precise error analysis. Usually the cause of the problem can be determined remotely so that the service call can quickly and systematically solve the problem. This secures the plant operator's financial returns that would have been lost if the malfunction was not immediately detected. Additionally, the installer saves valuable time.

Avoid yield losses

Monitoring has become essential for the solar industry and is almost always included for new PV plants. Looking at the past, it can be said that the role of monitoring today is much more vital to PV plants. Even if PV plants were equipped with a monitoring system, then the control of operation data left much to be desired in most cases. Monitoring was often absent and plant owners often had not yet upgraded their PV plants.

Numerous factors could negatively influence the operation of a PV plant and could lead to a reduction or, in the worst case, to complete yield losses. The failure of one or several inverters, cable damage, errors during installation or reductions from the modules due to dirt and grime are only just an example. A professional monitoring system such as the Solar-Log Energy Management System is required to recognize and fix such problems in time. It is even better to have a monitoring system that is attended to by a PV installer/EPC along with a service and maintenance contract.

Solar-Log Dashboard

Based on a study with a focus on the question: "Which losses occur with PV plants when various components fail," the manufacturer of the Energy Management System Solar-Log (Solare Datensysteme GmbH), could verify the advantages of installing a professional monitoring system.

An example from the study: Partial failure of one or several inverters

PV Plant data

Total Power

52.38 kWp

Inverter Power (INV 4+5)

20.16 kWp

Percentage INV 4+5 w/plant

38.5 %

No. of inverters


Performance of inverters

2x4; 2x6. 3x10 kW



Plant completion

June 2006

Two of the seven inverters were not working for 31 days in August 2015.

Total yield August 2015 all inverters


Total yield August 2015 all inverters

7,442 kWh

Yield August 2015 (INV 4+5)

2,904 kWh

Average yield per day (INV 4+5)

93,70 kWh

Breakout time of the PV Plant

Energy loss

31 days

2,904 kWh

5 days

468 kWh

Difference / saving

2,436 kWh

The plant owner had a loss of 2,904 kWh since two of the plant's inverters were offline for 31 days and the failure was not immediately detected, reducing the actual PV production greatly.

With a professional monitoring system like Solar-Log, failures like this can be detected instantly. Within about five days, the installer can fix the failures. In this case, the loss would have then only been 468 kWh, preventing a loss of 2,436 kWh.

This example shows that an investment in a Solar-Log Energy Management System is worthwhile in any case.

The challenges of professional monitoring

It has to be possible to monitor all of the components connected to the PV plant. These components include, for example: devices such as inverters, meters, sensors and battery storage systems - in case of malfunctions or outages; individual strings which require immediate reactions in case of a drop in performance or outage; the module fields - to detect damages or installation errors; and production and consumption data - to check the consumption of various appliances. If a malfunction of a component or a performance drop of a string is detected, the system then has to reliably notify the installer or PV plant operator about what has happened and which component is involved.

It is also necessary to define what exactly should be monitored based on the particular PV plant and components. Monitoring a small PV plant with one inverter is less complex than monitoring a large plant with several dozen inverters.

Data communication

Malfunction notifications and other information about the PV plant can be sent to the installer and/or PV plant operator via text message (SMS) or e-mail. It is also possible to access the data directly at the data logger, via the web portal and/or app. The data from the data logger is transferred to the web portal via the Internet. The data transfer methods have not changed much in recent years, but data visualization has been optimized. The data can now be presented more concisely and with more detail.

The plant operator needs to have a constantly active Internet connection so that communication is maintained, ensuring that malfunctions and errors are immediately recorded, logged and forwarded.

Today's monitoring systems

Today's optimal monitoring systems consist of a manufacturer-independent monitoring device (data logger) and a web portal. With the system, it is possible to monitor all of the PV plant components to detect malfunctions and to report these malfunctions to the installer and/or plant operator. The web portal has to be able to concisely visualize all of the important plant data. Additionally, the system has to be compatible with components such as heat pumps, combined heat and power systems (CHP), heating rods, all major inverters and sensor boxes.

Written by Marco Weinmann, Public Relations & Marketing for Solar-Log

Labels: solar monitoring,Solar-Log,solar power plant,yield loss

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